Guidance on DOI registration for a combined article

I work for a small Australian publisher. One of our society partners wants to publish a piece consisting of 4 separate articles (all separately peer-reviewed) in the same paper brought together with a short introduction, resulting in a combined paper with one DOI. However, they also want each separate article to have its own DOI.

I’m not sure if this is possible because then we would be publishing each paper separately - but then republishing the same content as part of the combined article under a different DOI.

We want to recommend publishing each article separately and just using references and links in the introductory piece to link them all together.

I’d appreciate advice on how to handle this - or best practice on what to do in this scenario.

Thanks
Emma